DE2634156A1 - METHOD OF MANUFACTURING MAGNETIC HEADS - Google Patents

Description

relating to methods of manufacturing magnetic heads

The invention relates to methods of manufacturing a magnetic head.

The performance of magnetic heads is primarily determined by the accuracy with which the magnetic gap is formed leaves. In a small-sized magnetic head or a miniature magnetic head to which the invention is based refers, the width of the gap measured in the direction of travel of the magnetic tape is about 1 to 2 micrometers, and it is extremely difficult to produce a gap with such a width with high accuracy. To now it is common practice to form such a gap by placing two core block parts for a magnetic head side by side arranges that their surfaces delimiting the gap are opposite one another, with one another between the two surfaces a spacer in the form of a thin sheet of mica or metal foil is located. A gap-limiting material is then applied brought to melt and caused to penetrate into the space between the two gap delimiting surfaces is kept free by the presence of the spacer, whereupon the material is allowed to solidify. Applying this Process leads to high manufacturing costs, since the

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The material of the spacer is expensive and because it causes considerable difficulties in making such a spacer edit so that it has a thickness of 1 to 2 microns with high accuracy.

The invention has for its object to provide a method of manufacturing a magnetic head in which the above mentioned difficulties in creating a narrow gap in a magnetic head of small dimensions can be avoided and that allows the core of a magnetic head without using a spacer with a To provide gap of high accuracy predetermined width.

To solve this problem, the method provides that two core block parts are provided, each of which is one Gap-delimiting surface has that two separated by a distance Regions of one of the core block parts within the gap delimiting surface with an etchant opposite Resistant material, e.g. aluminum, are covered that the gap delimiting surface of one core block part is etched with the aid of an ion beam or by ejecting a plasma in order to create a recess whose Depth is equal to the desired gap width that the two core block parts are brought to bear against one another, so that their gap delimiting surfaces are opposite each other, so that a gap-forming or gap-filling material in a free one Space is introduced between the gap delimitation surfaces of the two core block parts as a result of the etching of a of the gap delimiting surfaces is present that the gap filling material melted and caused to enter the free space that the gap filler the possibility is given to solidify, so that a core block with a gap of the desired width is formed, and that the core block is cut to the desired dimensions so that one or more cores are obtained. Refinements of this The method emerges from the subclaims.

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The invention is described in more detail below explained with reference to schematic drawings of exemplary embodiments. It shows:

1 shows a perspective view of a core block part to be used in the method according to the invention;

2 shows a vertical section of a device for generating an ion beam;

3 shows a perspective illustration of two core block parts arranged in contact with one another;

Fig. 4 is a perspective view of one according to the invention Method of manufactured core block;

5 shows a perspective illustration of a single core produced by the method according to the invention for a magnetic head;

Fig. 6 is a perspective view of another embodiment a core block part;

7 shows a perspective illustration of a plurality of core block parts arranged on top of one another;

8 is an end view of a further embodiment a core block part;

9 shows a perspective illustration of a core block part for use in the plasma spraying method according to the invention;

10 shows the structure of a plasma spray device;

11 shows a perspective illustration of two core block parts arranged in contact with one another;

FIG. 12 is a perspective view of a core block produced with the aid of the method according to the invention; FIG. and

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Pig. 13 is a perspective view of an individual made using the method according to the invention Kerns.

According to FIG. 1, a core block part 1 made of a ferromagnetic oxide material is first provided, which has two Has gap delimitation surfaces la, Ib, with which two strip-like Approaches are provided which extend along the longitudinal edges of the core block part. The opposite Snd sections of the gap delimitation surfaces la, Ib are covered with covers, for example with the aid of a corresponding template 2a, 2b, 3a and 3b made of a material, e.g. aluminum, which is resistant to etching.

According to FIG. 2, the core block part 1 is secured with the aid of two brackets 4a and 4b attached to a table 5. The brackets and the table consist of an anti-etching device resistant material like aluminum. The table 5 is arranged in an inclined position on a support rod 6, the also consists of a material that is resistant to etching. The through the named components The assembly formed is arranged in a chamber 8 of an ion beam spraying device 7, the left side wall of which according to FIG Fig. 2 has an opening 8a for introducing an ion beam which is supplied by an ion beam transmitter 9, which is arranged on the outer surface of the left side wall. The lower part of the right side wall of the chamber 8 is with a discharge opening 8b which is in connection with a discharge device (not shown).

The table 5 and the support rod 6 are both made hollow, and the interiors of these parts are provided with a flow of cooling water fed, e.g. by connecting the support rod 6 to a water supply device, not shown. aside from that the support rod 6 is coupled to a mechanical drive device, not shown, which is used to drive the table 5 to rotate together with the core part 1 arranged thereon at a speed of the order of 60 rpm.

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The chamber 8 is sealed and evacuated to an internal pressure on the order of 10 "" to 10 "Torr the ion beam transmitter 9 is put into operation so that an ion beam strikes the rotating core block part 1, after passing through the opening 8a. Depending on the desired value of the operating efficiency and the desired Surface quality of the polished surface, a corresponding angle is selected at which the ion beam hits the Target, i.e. the surface of the core block part 1, hits. As a result of the spraying action of the ion beam, the core block part 1 is etched to the desired depth, whereupon the transmitter 9 is switched off and the core block part 1 is removed from the device. After the covers 2a, 2b, 3a and 3b are removed have been, the areas that were immediately under the covers are compared to the remaining Part of the gap delimitation surfaces are higher because they were not exposed to the etching process. This increase in height corresponds to the desired gap width.

According to FIG. 3, this is produced in the manner just described Core block part arranged on the upper side of a second core block part 10 made of a ferromagnetic oxide material, which is designed as a flat surface. Then two round glass rods 11, only one of which in FIG. 3 is closed can be seen, arranged near the etched gap delimitation surfaces la and Ib and in a chemically neutral gas atmosphere Heated to its melting point, whereupon the molten glass 11 into the spaces between the two core block parts 1 and 10 penetrates. The assembly is then allowed to cool, so that the core block 12 shown in FIG. 4 is obtained. It can be seen that the free spaces between the gap limiting surfaces la, Ib of the core block part 1 and the second core block part 10 have been filled by the molten glass, which as a result of capillary action in this free spaces has penetrated, so that there are now two gaps Gl and G2 o The core block 12 thus produced is along cut to the planes indicated by the dashed lines a, b and c and then cut along dea through the

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Broken lines d, e, f, g, h, i and j designated planes in the manner shown in FIG. 4 in disk-like manner Pieces broken up so that a corresponding number of cores is obtained. One of these cores is shown in Fig. 5 and designated as a whole by 13; it is formed by core block part Ic and 10a, between which there is a gap G2a. Of course, the core block according to FIG. 4 can be cut to size in any desired manner and broken down into disc-like pieces. The cutting of the core block according to FIG. 4 along the planes indicated by the dashed lines a and c serves to remove unneeded sections that are located on the long sides of the core block. The core block 12 is intersected along its center plane indicated by the dashed line b, if a core with should only be made one gap. Cutting the core block along the two by the dashed lines d and j designated planes is also used to remove unusable sections of the core block 12, the the uncovered or unmasked surface parts of the core block part 1 used as the starting material according to FIG. correspond.

If a core is to be produced that has both a front and a rear gap, the core block is required 4 not to be cut along its central plane indicated by the dashed line b. if if appropriate distances are selected between the dashed lines e to i, any desired track width can be selected as shown in FIG T obtained transversely to the direction of travel of the magnetic tape. The gap width t depends on the depth to which the core block part 1 used as the starting material was etched, and therefore also according to the type of treatment of the core block part 1 in the chamber 8. By appropriate choice of the intensity of the ion beam, its angle of incidence and its Any desired etching depth can be achieved for duration of action. The glass material 11 of FIG. 3 can be in any use any shape, e.g. in the form of rods, blocks or a powder, and for use as a gap filler

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material are also other materials, e.g. ceramic materials or email, usable. The top of the second core block part 10 need not be designed as a flat surface but it may have a V-shape of shallow depth or a concave curvature.

Fig. 6 shows a further embodiment of a core block part 14 with only one gap delimiting surface 14a on one longitudinal edge, in which one surface piece at each end is covered with a mask 15a or 15b. The core block part 14 can be used instead of the core block part 1 described. According to FIG. 7, several such core block parts can be used place them on top of each other and at the same time expose them to the action of the ion beam to spray material.

8 shows a further example of a core block part 16 which can be used instead of the core block part 1. The core block part 16 has several gap delimiting surfaces 16a, 16b, 16c and 16d at a corresponding number of approaches, so that using such a core block part it is possible to have an even larger number of cores in one in a single operation.

It was described above that the gap delimitation surfaces the core block parts are etched with the help of an ion beam, but it is also possible to use a bombardment with a plasma containing electrons and ions. The core block parts used here can be a have a shape similar to that described above.

An example is shown in Fig. 9 in the form of a core block part 21 made of a ferromagnetic oxide material, the two has strip-like approaches that extend over its longitudinal edges and form two gap delimitation surfaces 21a and 21b. Surface pieces at the opposite ends of the two gap delimitation surfaces are resistant to etching Masks 22a, 22b, 23a and 23b covered, which for example consist of aluminum and with the help of a corresponding

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Stencil to be applied. According to FIG. 10, the core block part 21 according to FIG. 9 attached to a support 25 with the aid of two holders 24a and 24b. Support or the table 25, like the holders 24a and 24b, consists of an etching process Material like aluminum. The support 25 is in a bell 27 of a device 26 for spraying material arranged by means of a plasma jet.

The bell 27 is tightly closed and up to an internal pressure evacuated on the order of 10 "Torr and then filled with a chemically neutral gas such as argon, with a

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Maintain internal pressure on the order of 1 to 3 10 Torr will. The bell contains a filament 28, an anode 29 and an auxiliary anode 30. A current is conducted through the filament 28 and if a voltage is applied between the anode 29 and the auxiliary anode 30, arises in the bell 27 a plasma 31, which by applying an external magnetic field by means of an electromagnetic coil 32 around the central axis the device is focused.

If the target electrode or the workpiece is at a negative direct voltage potential compared to the potential of the plasma held, the positive ions contained in the plasma bombard the support 25, so that the surface atoms of the core block part 21 arranged thereon are sprayed. This process is ended as soon as the core block part 21 has been etched to the desired depth, whereupon it is removed from the bell 27; then the masks 22a to 23b removed, so that a core block part is obtained, in which the surface pieces immediately under the masks were, compared to the gap delimiting surfaces are increased by an amount that corresponds to the desired gap width.

The core block part 21 obtained in this way is arranged on top of a second core block part 33 according to FIG. 11, which consists of a ferromagnetic oxide material, and the top of which forms a flat surface. Then two rounds

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Glass rods 34, only one of which can be seen in FIG. 11, are arranged near the etched gap delimiting surfaces 21a and 21b and heated in a chemically neutral gas atmosphere to the melting point of the glass. Here the melted penetrates Glass 34 in the free spaces z \ tfischen the two core block parts 21 and 33. Then you leave the assembly cool, so that the core block 35 shown in FIG. 12 is obtained. The free spaces between the gap delimiting surfaces 21a, 21b of the core block part 21 and the flat top of the second core block part 33 are melted from the Filled glass, which penetrates into them as a result of capillary action, so that the gaps G3 and G4 are formed. Now the core block 35 according to FIG. 12 along the through the dashed lines al, bl and el cropped to specific planes and along the lines dl, el, fl, gl, hl, il and jl dismantled into disc-like pieces. That way it gets a plurality of cores, one of which is shown in FIG. 13 and designated as a whole by 36; this core consists of the Core parts 21c and 33a and has a gap G4a. The core block according to FIG. 12 can also be cut to size in any way and broken down into disk-like sections. The cutting of the core block along the lines indicated by the dashed Lines marked al and el are used to remove the unusable parts on the long sides of the core block 35 are present. If cores are to be produced with only one gap, the core block 35 is along the intersected by the dashed line bl denoted central plane. The cutting of the core block along the dashed lines dl and jl are used to remove the previously masked parts. Should a core be created that has both has a gap on the front as well as on the back, the core block 35 does not need along the dashed line Line bl to be cut through «By appropriate choice of the distances between the dashed lines el to il ist it is possible according to FIG. 13, any desired gap height or track width To achieve tl. The gap width ti depends on the depth to which it was used as the starting material

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Core block 21 was etched, i.e. according to the type of treatment of this core block part in the bell 27 according to FIG. 10. More precisely said, the gap width ti is determined by the intensity of the plasma, its angle of incidence and its duration of action certainly. As mentioned, instead of the glass rods 34 one could also use a filler material in another form, for example blocks or a powder. In addition, the use of other materials, e.g. ceramic material or enamel, is possible as gap filling material. The top of the core block part 33 does not need to be flat, but it can also given other shapes such as the shape of a V-shaped surface of shallow depth or a concave curved surface.

A special process is described below which makes it possible to use an etching process or by spraying Material Gap boundary surfaces on a core block part with high accuracy and with a high degree of efficiency to train. Since the method can be applied to any type of core block parts, it will be referred to below in relation to of the core block part according to FIG. 1 besehrieben. The core block part 1 is immersed in an etching solution such as hydrochloric acid to etch the unmasked gap delimitation surfaces la and Ib. Once the core block part is etched away to a depth which corresponds to almost half of the desired gap width, it is removed from the etching solution and completely Removal of acid subjected to ultrasonic cleaning. The core block part is then placed together with the masks or covers in the ion beam material atomization device 7 according to FIG. 2 or in the plasma atomization device 26 brought to Fig. 10 to continue the process of etching the gap delimitation surfaces la and Ib and the etching depth and thus to bring the gap width to the desired final value with a high degree of accuracy. In this way it is possible to shorten the total working time required for etching the gap delimiting surfaces to a predetermined depth, so that the method is suitable for use in mass production on the one hand, but high accuracy on the other hand the achieved gap width guaranteed.

Claims: 609885/0908

Claims (4)

EXPECTATIONS A method of manufacturing magnetic heads, characterized in that two core block parts are provided each of which has at least one gap delimiting surface that in one of the core block parts at least two regions of the or each gap delimiting surface separated by a distance are covered with the aid of a masking material that the or each gap delimiting surface this core block part is exposed to a jet causing the spraying of particles in order to bring them up to to a predetermined depth so that the two core block parts are placed in contact with each other so that the or each gap delimiting surface of the first-mentioned core block part of the gap delimiting surface of the other core block part opposes that a gap filling material is melted and caused to be in a free space penetrate between the opposing gap delimitation surfaces, so that the gap filling material solidifies leaves to get an assembly in the form of a core block, and that the core block is cut to size and in disk-like form Sections is disassembled to obtain multiple cores. 2. The method according to claim 1, characterized in that an ion beam to the beam for spraying material particles heard. 3. The method according to claim 1, characterized in that a plasma to the beam for spraying material particles heard. 4. The method according to claim 1, characterized in that the or each gap delimiting surface of the one core block part after covering with a masking material, but before the step of spraying material particles by means of a Acid is etched. L e r s e i t e